The knife on a typical cutting header of an agricultural harvester, such as a combine or crop mower, comprises a knife assembly comprising a knife bar extending along the front lower edge of the header, with triangular knife sections attached along the bar such that the apex of the triangle extends forward from the bar. The exposed side edges of the knife sections are sharpened. The knife assembly also includes guards attached to the front lower edge of the header that serve to protect the knife sections from breakage when contacting stones and like obstructions. The guards comprise pointed guard fingers extending forward, and the knife moves back and forth along the edge of the header in a slot cut laterally through the guard fingers. In addition to protecting the knife, the guard fingers also enable the knife sections to cut the crop. As the knife section moves back and forth it pushes crop against the sides of those portions of the guard finger that are above and below the slot, shearing the crop stalks.
Much loss often occurs in straight cut harvesting of crops such as dry beans, peas, milo, canola, and sunflowers due to heads or pods shattering or falling below the cutter bar. Dry, fragile seed pods often shatter when contacted by the harvesting equipment before they are on the header, and the shattered pods spill their seeds to fall on the ground. Seeds fall from the shattered pods down through the knife to the ground. While this problem of shattering seed pods and heads is more severe in some crops than others, there is generally at least some shattering loss in any crop.
Seed pans have been developed that attach to the front edge of the header and extend forward of the knife. The pans are spaced to form slots between the pans. The crop plants pass along the slots and are cut by the knife at the rear end of the slots. Seeds falling from the plants are caught in the pans and work their way rearward and onto the knife. Such seed pans are disclosed for example in U.S. Pat. Nos. 2,575,120 to Peel and 6,032,445 to Heintzman. The top surfaces of the pans are flat, with raised side walls to keep the seeds on the pan. The pans are configured to slope downward from front to rear so that the seeds move down the sloping surface onto the header and into the harvester.
These seed pans are configured so that the slots between the pans are spaced to match the row spacing of the crops being harvested. Thus a large part of the knife is covered and not used. The Peel pans are rounded from a point in the center of the front end to guide the plant stalks into the slots. The leading ends of the Heintzman pans are pointed, and have different tapers on each side, and every other pan is shorter than the intermediate pans. The side edges on each catch pan taper from the point, located in the center of the pan, at different angles on the opposite edges such that the tapered edges on each pan are different length. Heintzman states that this configuration provides different loads and positioning on the stalks as they are moved to aid in guiding the grain stalks into the slot between adjacent pans.
The Peel and Heintzman pans have their front points in the center of the pan so that plant stalks that are contacted by the pan are moved substantially equally to each side of the pan. In both as well, the seed pans are mounted so that a guard finger is in the center of the rear end of the slot.
U.S. Pat. No. 5,105,610 to Britten discloses crop stalk guides for attachment to a harvest header in solid seeded crops where plants are in narrow rows which are not followed when harvesting, as the harvester drives without regard to the rows, and the plants are considered to be spread generally evenly across the width of the header. The Britten guides do not appear to catch falling seeds, as the guides comprise plates with flat top surfaces which have no walls to prevent seeds from falling off, but rather are simply used to guide the crop stalks into the knife. A plate is mounted to the tops of two adjacent guard fingers and extends forward. The plates are mounted to the guards such that all guard fingers are covered by a plate, and the ends of the slots lie between adjacent guard fingers.
The plates have a point in the middle of the front end and guide the contacted stalks equally to each side and along a slot between the plates to the knife. The slots are much narrower than the spacing between the guard fingers, so at the rear ends of the slots where the knife is located, the plates must be notched so that the outer edges of the guard fingers are exposed to the knife sections to allow the knife sections to shear the stalks against the guard fingers.